This invention relates generally to automatic vents used in heating and/or cooling systems, and more particularly to an automatic vent having a multi-hinged valve that allows the automatic vent to operate at a greater pressure differential within a compartment of the system intended to vent gas.
Automatic vents provided in heating and/or cooling systems are well known in the art. Reference can be made to U.S. Pat. Nos. 2,677,387 to Crawford, 3,002,522 to Klinefelter, 3,018,787 to Kirk, Jr., 3,394,724 to Klinefelter, 3,599,659 to Nuter, and 4,299,248 to Becker et al. as representative prior art in this area. The function of such a vent is to automatically vent unwanted gases from a compartment intended to contain fluids to a surrounding compartment containing only gases. The fluid compartment is under higher pressure than the surrounding compartment. In a hot water heating system, gas (e.g., air) initially present in the system prior to the system being filled with fluid (e.g., water) or air dissolved in the water and later liberated as the water temperature rises moves from the compartment to the surrounding compartment. The automatic vent exhausts the gas to the surrounding compartment thereby, removing air from the system.
Referring to FIGS. 1 and 2, which illustrate a typical prior art automatic vent generally indicated at 10, the automatic vent 10 comprises a cup 12 that defines a compartment 14, a float 16 that is positioned within the compartment 14, and a close off valve assembly 18 that covers the upper end of the cup 12. Preferably, the automatic vent 10 is positioned at the high point of the system. Due to buoyancy, gas (air) rises to the high point and enters the cup 12 from the system. As more gas accumulates within the cup 12, the fluid (water) level and the float 16 recedes or moves downwardly within the cup 12 thereby causing a valve 20 of the close off valve assembly 18 to open. As gas is being expelled from the automatic vent 10, the fluid level and the float 16 rise again within the cup 12 while the close off valve 20 closes. In this manner, only gas (air) is vented while the fluid (water) is retained in the pressurized compartment of the cup 12.
The valve assembly 18 and float 16 combine to form what is typically called in the industry a "floating lever" mechanism. Floating levers have advantages and disadvantages as compared with other designs. One advantage is that they are largely self-cleaning, thus less susceptible to dirt contamination. Another advantage is that they provide a higher venting rate than other vent designs. The main disadvantage of floating levers is that they offer a relatively reduced pressure differential in which gas is vented from the compartment to atmosphere.